Drop-on-demand ink jet printers use thermal energy to produce a vapor bubble in an ink-filled chamber to expel a droplet. A thermal energy generator or heating element, usually a resistor, is located in the chamber on a heater chip near a discharge nozzle. A plurality of chambers, each provided with a single heating element, are provided in the printer's printhead. The printhead typically comprises the heater chip and a nozzle plate having a plurality of the discharge nozzles formed therein. The printhead forms part of an ink jet print cartridge which also comprises an ink-filled container.
Ink jet printers have typically suffered from two major shortcomings. First, optical density of a printed image varies greatly with the print media or substrate being printed upon. Second, ink drying time is excessive.
Attempts to solve these problems through ink formulation have resulted in a loss of performance in other areas, and in general any change made to solve one of the two problems has resulted in aggravation of the other problem.
Heating stations positioned before, coincident with and after the print zone can improve optical density and drying time, but at the expense of power consumption and machine complexity. Hence, this solution has not been found desirable.
Accordingly, there is a need for an improved ink jet printer which is capable of printing images uniformly well on a wide variety of commercially available substrates and wherein ink drying time is minimized.